An Arunachal Pradesh MP has sounded the alarm after Siang – the river that rises in Tibet as Yarlung Tsangpo and meets two others in Assam to flow as the Brahmaputra– turned “unnaturally muddy”, attributing it to China’s river diversion plan.

But anti-dam activists in the state do not find any issue with the Chinese design on Tsangpo, including a plan to divert water to parched Xinjiang via a 1,000km tunnel. Reason: If no water flows down from Tsangpo, New Delhi will be forced to shelve the 10,000-megawatt hydropower project on Siang.

Pasighat, the headquarters of East Siang, is 560km north-east of Guwahati. The town is dominated by Adi tribe, who revere the river as Aane (mother).

“Exploitation of the upper reaches of Siang (Tsangpo) has already begun. China has probably started constructing the 1,000km tunnel to divert the river to Xinjiang,” he said.

Beijing has rejected there exists any plan as such.

“I have grown up in Pasighat, and I know Siang (water) is so clear in November that you can see the riverbed. Now, the water is not only muddy, it seems there’s cement in it, which could be from the tunnel that China is probably constructing,” the Congress leader said.

Officials said more samples have been sent. They feared for the aquatic life if the river continues to be “this turbid”.

The findings, however, have not perturbed the anti-dam groups such as Forum for Siang Dialogue (FSD), Siang People’s Forum and Adi Students’ Union.

“Our people are happy there will be no more water to make a big dam and their agricultural lands will be saved from getting submerged. Water for drinking and irrigation comes from small rivers and rivulets and not from Siang,” FSD general secretary Vijay Taram told HT.